A dietary achievable dose of microencapsulated DHA increases the Omega-3 Index without affecting body composition in physically trained male and female adults

This study investigated body composition and time-course changes in the Omega-3 Index (O3I; %EPA + DHA of total erythrocyte fatty acids) following a dietary achievable dose of microencapsulated docosahexaenoic acid (DHA) in physically trained adults (n = 38, 37% female). A double-blind, placebo-controlled, pair-matched design was used to allocate participants to either the control (n = 12, sunflower oil) or the DHA group (n = 26). Participants in the DHA group consumed fish-derived (n = 13, 736 mg/d DHA) or algae-derived (n = 13, 694 mg/d DHA) microencapsulated chewable DHA tablets daily for 12 weeks. Body composition was assessed using DEXA at week 0 and 12. Finger stick blood samples were collected at week 0, 4, 8 and 12 to measure whole blood fatty acid profiles, and the derived O3I. Data presented as mean (95% CI). There was no interaction effect or main effect of group for any body composition metric (all P > 0.05). At week 0 no significant difference was observed between groups for O3I (control: 4.75% [95% CI; 4.19, 5.30]; DHA: 4.89% [95% CI; 4.53, 5.24], P = 0.622). Following 12 weeks of DHA supplementation a group*time interaction was observed for O3I (P < 0.001), such that O3I increased in the DHA group at week 4 and 8 and plateaued between week 8 and 12 (control: 4.76% [95% CI; 4.30, 5.23]; DHA: 7.36% [95% CI; 7.05, 7.68], P < 0.001). A dietary achievable dose of DHA, delivered as microencapsulated tablets, increased the O3I over 12 weeks in physically trained adults but did not meaningfully alter body composition.